1. Field
This application relates generally to wireless communication, and more specifically but not exclusively to media access control for an asynchronous wireless system.
2. Background
Various network topologies may be employed to establish wireless communication. For example, a wide area network, a local area network, or some other type of network may be deployed depending on the particular wireless communication capabilities that are needed for a given application.
A wireless wide area network is typically a planned deployment within a licensed frequency band. Such a network may be designed to optimize spectral efficiency and quality of service to support a large number of users. A cellular network is one example of a wireless wide area network.
A wireless local area network is often deployed without centralized planning. For example, such a network may be deployed in an ad hoc manner in unlicensed spectrum. Consequently, this type of network may be used to support a single user or a small number of users. A Wi-Fi network (i.e., an IEEE 802.11-based network) is one example of a wireless local area network.
In practice, each of the above networks has various disadvantages due to tradeoffs that may be made to provide a given type of service. For example, due to the complexity of centralized planning, setting up a wireless wide area network may be relatively expensive and time consuming. Hence, such a scheme may not be well suited for “hot spot” deployments. On the other hand, an adhoc network such as Wi-Fi may not achieve the same level of spatial efficiency (bits/unit area) as a planned network. Moreover, to compensate for potential interference between nodes in the network, a Wi-Fi network may employ interference mitigation techniques such as carrier sense multiple access. Such interference mitigation techniques may, however, lead to poor utilization and provide limited fairness control, and may be susceptible to hidden and exposed nodes.